JPH01159047A - Production of microcapsule - Google Patents

Abstract

PURPOSE:To convert a core substance into a microcapsule merely by mixing with the core substance and to improve alkali resistance and heal resistance by cross-linking starch grains and then decomposing their inner part with a raw starch decomposition enzyme. CONSTITUTION:Starch grains are cross-linked by using a method such as phosphorus linking with sodium trimetaphosphate, linking with epichlorohydrin, etc. The inner part of these cross-linked starch grains are then decomposed with a starch decomposition enzyme such as alpha-amylase, beta-amylase, etc. The treated starch grains are dehydrated by filtering, centrifuging, etc., and dried after being washed with a solvent such as water or methanol. It is possible for these treated starch grains to include and protect a core substance within them by merely mixed with the core substance. The obtained microcapsule has properties of alkali resistance, acid resistance, heat resistance and biodegradation, and is used, therefore, for agricultural chemicals.

Description

Detailed Description of the Invention (Industrial Application Fields) Microcapsules are used in foods, pharmaceuticals, agricultural chemicals, industrial applications, etc. to encapsulate fragrances, pigments, drugs, etc., to protect and stabilize them, and to powderize liquid substances. It is widely used in various fields such as applications.

(Prior art) Microcapsule manufacturing methods include chemical methods such as interfacial polymerization, physicochemical methods such as phase separation from an aqueous solution, and mechanical methods such as air suspension coating. There are various methods. (For example, Asashi Kondo, "Industrial Technology Library 25 Microcapsules" (April 20, 1972), Nikkan Kogyo Shimbun, P30-1 The procedure for manufacturing microcapsules is generally (1) microcapsules in an encapsulation medium. Disperse the substance (hereinafter referred to as core substance) to be placed in the system into fine particles. (2) Introduce a substance that will form the wall into this system. (3)
By some method, the wall material is polymerized around the core material particles,
Deposit, enclose, and shape the capsule wall. (4) Strengthen the capsule wall chemically or physically to form a stable membrane. Consisting of

(Problems to be Solved by the Invention) Microcapsules have been manufactured by the various methods described above. The disadvantage is that it is chemically and physically damaged and changed. Furthermore, since it is necessary to disperse the core substance in the form of fine particles, there is a drawback that the equipment becomes large.

In addition, in interfacial polymerization methods, etc., the wall material is a synthetic polymer;
There is a drawback that it cannot be used for food purposes.

(Method for Solving the Problems) In order to solve the above problems, the present inventors have conducted various studies and found that if starch particles are cross-linked and a raw starch-degrading enzyme is applied, only the internal portions are decomposed and micro- He discovered that capsules could be made and completed the invention. The enzyme that breaks down raw starch is Aspergillus awamori (Aspergillus awamori).
glucoamylase of Rhizopus avamori, amylase of Rhizopus sp.
xa) amylase and the like are known. (For example, Hiroshi Ishigami, Starch Science, 38.66 (1987)). but,
When unprocessed raw starch is broken down by these enzymes, the starch particles become porous and extremely brittle. Furthermore, it is difficult to use as microcapsules because it easily gelatinizes and the particles collapse when heated. As a result of extensive research, we have found that when these enzymes are applied to crosslinked starch particles, the number of holes is reduced and the mechanical strength increases. They also discovered that it is possible to produce microcapsules that do not gelatinize even when heated.

For crosslinking in the present invention, commonly used phosphoric acid crosslinking using phosphoryl chloride or sodium trimetaphosphate, crosslinking using epichlorohydrin, or other crosslinking can be used. (For example, Roy L.

Whistler et al. Starch Chemistry
y and Technology second ed
tionsJ (1984') P 324-326
) The degree of crosslinking is expressed by the degree of swelling of starch particles.

What is swelling degree? Take 100 mg of starch sample, suspend it in 10 mQ of electrolyte solution (a solution containing 10% zinc chloride and 26% ammonium chloride in distilled water), and suspend it in a hot water bath (95°C).
After heating for 5 minutes (above), cool to 20℃, shake thoroughly, transfer to a 10mQ graduated cylinder, and heat at 20℃ for 12 minutes.
The swelling volume of the sample inside the cylinder when left standing for a period of time is mQ.
It means the numerical value expressed as , and indicates the degree of crosslinking of starch.

In the present invention, the degree of crosslinking is expressed as the swelling degree, which is 3 m
It is desirable to make it less than fi, preferably less than 1 mQ.

When the inside of crosslinked starch particles is decomposed by a raw starch-degrading enzyme, gelatinization and decomposition of the inside can be promoted by heating and/or addition of amylase such as α-amylase and β-amylase. If necessary, crosslink again after decomposition to crosslink the inside.

Furthermore, mechanical strength can also be increased.

The starch particles after decomposition are washed with water or a solvent such as methanol, dehydrated by filtration and centrifugation, and dried.

The size of the microcapsules of the present invention depends on the type of raw starch,
The particle size can be adjusted from several μ to several 100 μ. In addition, the size of the pores in microcapsules varies from a fraction of a micrometer to several tens of microns depending on the type of raw starch, particle size, degree of crosslinking, enzyme freshness, etc.
It can be adjusted up to 00μ.

(Function) Since the present invention is configured as described above, a core material is not required when manufacturing microcapsules. Therefore, the core material can be microencapsulated simply by mixing the microcapsules of the present invention and the core material, which do not cause chemical or physical damage or change to the core material. Therefore, the equipment required for microencapsulation can be made smaller. Microcapsules can also be formed by mixing the microcapsules of the present invention with a solution in which the core substance is dissolved or dispersed in water, oil, or an organic solvent.

Since the microcapsules of the present invention are crosslinked starch, they have alkali resistance, acid resistance, and heat resistance. Furthermore, since it is biodegradable, it can also be used as sustained-release microcapsules for pesticides, etc.

(Examples) Example 1 100 parts of cornstarch was dispersed in 200 parts of water, 0.4 parts of caustic soda was added, and the mixture was stirred at 40°C for 1 hour. 10 parts of sodium trimetaphosphate was added, the mixture was adjusted to PHII with a 0.1 N aqueous sodium hydroxide solution, and stirred for 8 hours to effect crosslinking with phosphoric acid. It was filtered, washed thoroughly with water, and further filtered and dehydrated. The degree of crosslinking of this crosslinked starch was 1, Omfi, when the degree of swelling was measured.

This crosslinked starch was dispersed in 200 parts of water, the pH was adjusted to 5.5 with 0.1N hydrochloric acid, 0.1 part of Kokugen K (Daiwa Kasei SM, raw starch degrading enzyme) was added, and the mixture was heated at 40°C for 24 hours. Stirred. The mixture was heated to 70° C. to inactivate the enzyme, filtered, thoroughly washed with water, filtered, dehydrated, and dried. When observed under a microscope, each particle had 3 to 5 microns and 1 to 2 holes.

As a result of mixing this microcapsule Log with 50 g of soybean oil, the soybean oil was microencapsulated and became smooth granules.

Example 2 100 parts of potato starch was dispersed in 200 g of water, 0.4 part of caustic soda was added, and the mixture was stirred at 40°C for 1 hour. 0.1 part of epichlorohydrin was added, the pH was adjusted to 11 with a 0.1N aqueous sodium hydroxide solution, and the mixture was stirred for 8 hours to form epichlorohydrin crosslinks. It was filtered, washed thoroughly with water, and further filtered and dehydrated. The degree of crosslinking of this crosslinked starch was 0.7 mfi when the degree of swelling was measured.

This crosslinked starch was dispersed in 200 parts of water, the pH was adjusted to 5.5 with 0.1N hydrochloric acid, and 0.2 parts of Kokgen K was added.
The mixture was stirred at 40°C for 24 hours. The enzyme was inactivated by heating to 70°C, filtered, thoroughly washed with water, further filtered, dehydrated, and dried. When observed under a microscope, there are 10 to 30 particles per particle.
There were one or two μ holes.

300 g of a 50% aqueous suspension of lead chromate suspended in a ball mill and 100 g of the present microcapsules were mixed, dried, and then sieved through a 300-mesh sieve. The microcapsules remaining on the sieve were bright yellow and became smooth particles. The angle of repose was measured to be 27°, indicating very fluidity.

(Effects of the Invention) As is clear from the examples, the microcapsules of the present invention can include the core substance therein and can be protected and stabilized simply by mixing the microcapsule with the core substance. Also, liquid substances can be turned into powder. Furthermore, no chemical or physical damage or changes are caused to the core material during microencapsulation.

Since the present microcapsules are made of starch, they are biodegradable and can be used for food and pharmaceutical purposes, and can also be used as a sustained release agent for agricultural chemicals.

Claims (2)

[Claims] (1) A method for producing microcapsules, which comprises crosslinking starch particles and decomposing the inside thereof with a raw starch-degrading enzyme. (2) The manufacturing method according to claim 1, wherein the crosslinking is phosphoric acid crosslinking and/or epichlorohydrin crosslinking.